I have installed a Gigabyte GA-EP43-UD3L, an Intel E6750 Dual Core 2 CPU. GeForce 8600 GT and 3G Memory.
The problem is that when I start the PC the CPU Fan will not work and neither will the fan connected to a System Fan Header. The four lights come on and stay on below the CPU fan header also there is no acknowledging beep.When attached to Monitor -there is no pic or noise. All connections treble checked and seem OK. Checked the memory and no change if any removed.
Has anybody got a clue what is causing this, I have built a few PC's but nothing like this .

Check:

• Fans work independent of being connected to the board.
• Fans are of the speed control variety and the function and order of the leads match board header pins.
• Power supply.

Then:
Do a complete rebuild from square one.

Finally, if problem persists:
Try another board.

Might also give Gigabyte a call. According to the board's documentation, those LEDs indicate CPU loading and the board has some whiz-bang power saving features. Sounds as if board is partially on, if that's possible. *shrug*

A new Motherboard fixed the problem.